@@ -1499,6 +1499,8 @@ void snd_usbmidi_disconnect(struct list_head *p)
spin_unlock_irq(&umidi->disc_lock);
up_write(&umidi->disc_rwsem);
+ del_timer_sync(&umidi->error_timer);
+
for (i = 0; i < MIDI_MAX_ENDPOINTS; ++i) {
struct snd_usb_midi_endpoint *ep = &umidi->endpoints[i];
if (ep->out)
@@ -1525,7 +1527,6 @@ void snd_usbmidi_disconnect(struct list_head *p)
ep->in = NULL;
}
}
- del_timer_sync(&umidi->error_timer);
}
EXPORT_SYMBOL(snd_usbmidi_disconnect);
@@ -2301,16 +2302,22 @@ void snd_usbmidi_input_stop(struct list_head *p)
}
EXPORT_SYMBOL(snd_usbmidi_input_stop);
-static void snd_usbmidi_input_start_ep(struct snd_usb_midi_in_endpoint *ep)
+static void snd_usbmidi_input_start_ep(struct snd_usb_midi *umidi,
+ struct snd_usb_midi_in_endpoint *ep)
{
unsigned int i;
+ unsigned long flags;
if (!ep)
return;
for (i = 0; i < INPUT_URBS; ++i) {
struct urb *urb = ep->urbs[i];
- urb->dev = ep->umidi->dev;
- snd_usbmidi_submit_urb(urb, GFP_KERNEL);
+ spin_lock_irqsave(&umidi->disc_lock, flags);
+ if (!atomic_read(&urb->use_count)) {
+ urb->dev = ep->umidi->dev;
+ snd_usbmidi_submit_urb(urb, GFP_ATOMIC);
+ }
+ spin_unlock_irqrestore(&umidi->disc_lock, flags);
}
}
@@ -2326,7 +2333,7 @@ void snd_usbmidi_input_start(struct list_head *p)
if (umidi->input_running || !umidi->opened[1])
return;
for (i = 0; i < MIDI_MAX_ENDPOINTS; ++i)
- snd_usbmidi_input_start_ep(umidi->endpoints[i].in);
+ snd_usbmidi_input_start_ep(umidi, umidi->endpoints[i].in);
umidi->input_running = 1;
}
EXPORT_SYMBOL(snd_usbmidi_input_start);
USB MIDI driver has an error recovery mechanism to resubmit the URB in the delayed timer handler, and this may race with the standard start / stop operations. Although both start and stop operations themselves don't race with each other due to the umidi->mutex protection, but this isn't applied to the timer handler. For fixing this potential race, the following changes are applied: - Since the timer handler can't use the mutex, we apply the umidi->disc_lock protection at each input stream URB submission; this also needs to change the GFP flag to GFP_ATOMIC - Add a check of the URB refcount and skip if already submitted - Move the timer cancel call at disconnection to the beginning of the procedure; this assures the in-flight timer handler is gone properly before killing all pending URBs Reported-by: syzbot+0f4ecfe6a2c322c81728@syzkaller.appspotmail.com Reported-by: syzbot+5f1d24c49c1d2c427497@syzkaller.appspotmail.com Cc: <stable@vger.kernel.org> Signed-off-by: Takashi Iwai <tiwai@suse.de> --- sound/usb/midi.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-)